Jack, I recently upgraded my 2 home PC's (Celeron's - circa 1998) to P4's w/digital music pkg, CD burner, DVD, etc. I did so basically because audio capabilities are so much improved, enhancing the reading and phonics programs we use. The graphics are also significantly improved over previous generation computers. Flat screens are more economical now, space saving and aesthetic, etc. DVD and music downloading capabilities make the home PC more of a home entertainment center.
When I purchased the new computers, I thought we might see an uptick in home PC sales as it's my belief that the new P4 systems are "next generation" when compared to P3 or Celeron. Didn't happen.
JMHO, FWIW. I'm no PC expert.